Concrete steps have long been relied upon for their strength, durability, and even aesthetics. The general use of “concrete” as a building material can be traced back to ancient Rome, where, like today, it was desirable to produce hardened structures of predetermined shape, size, and configuration from base materials easier to transport and manipulate as compared with, for example, naturally occurring stone or rock. In modern society, the compositions and uses of concrete have advanced significantly from Roman times, as might be expected.
One important advancement was the introduction of embedded supporting elements, such as rebar (i.e. reinforcement bar; reinforcing steel). Concrete, although possessing considerable compressive strength, has notably poor tensile strength. Rebar, generally made of steel rods, are frequently placed in molds, forms, etc. into which concrete will be added. The concrete structure is formed about the rebar, which serves to “absorb” tensile loads on the concrete. This significantly reduces the susceptibility of the concrete to fracture and breakage.
Today a commonly employed method for concrete manufacture is precasting. Reusable molds can be used to produce hundreds of identical standardized articles of concrete, such as precast wall slabs or precast concrete steps. Precasting is generally done in a centralized facility, and articles for individual construction applications are transported to their final destinations ready for use immediately after installation. Embedded rebar is critical in all such articles to meet requirements for load strengths and durability in both transportation and use.
The use of rebar or other embedded supporting elements carries with it certain drawbacks. In addition to material and transportation costs, rebar must be arranged in the desired configuration prior to pouring of wet concrete. Furthermore, rebar corrodes and weakens the concrete in its immediate vicinity such that localized breakdown of concrete is often observed. In the case of precast concrete steps, it is not uncommon for long fractures to form on a surface or side of the step adjacent and parallel to one or more bars of embedded rebar.
Edges formed by concrete, in particular the edges on concrete steps, experience little to no benefit from embedded rebar. Rebar helps absorbs overall deformation and fracture of a concrete article under tensile loading, but it does not offer any advantages to combat the routine localized loading and wear which occurs on surfaces and edges of the concrete structure. Cracking and crumbling are a pervasive problem with concrete edges, such as those of precast concrete steps.